Dietary monosodium glutamate increases visceral hypersensitivity in a mouse model of visceral pain.

BACKGROUND: Monosodium glutamate (MSG) has been identified as a trigger of abdominal pain in irritable bowel syndrome (IBS), but the mechanism is unknown. This study examined whether MSG causes visceral hypersensitivity using a water-avoidance stress (WAS) mouse model of visceral pain. METHODS: Mice were divided into four groups receiving treatment for 6 days: WAS + MSG gavage, WAS + saline gavage, sham-WAS + MSG gavage, and sham-WAS + saline gavage. The acute effects of intraluminal administration of 10 µM MSG on jejunal extrinsic afferent nerve sensitivity to distension (0-60 mmHg) were examined using ex vivo extracellular recordings. MSG was also applied directly to jejunal afferents from untreated mice. Glutamate concentration was measured in serum, and in the serosal compartment of Ussing chambers following apical administration. KEY RESULTS: Acute intraluminal MSG application increased distension responses of jejunal afferent nerves from mice exposed to WAS + MSG. This effect was mediated by wide dynamic range and high-threshold units at both physiologic and noxious pressures (10-60 mmHg, p < 0.05). No effect of MSG was observed in the other groups, or when applied directly to the jejunal afferent nerves. Serum glutamate was increased in mice exposed to WAS + MSG compared to sham-WAS + saline, and serosal glutamate increased using WAS tissue (p = 0.0433). CONCLUSIONS AND INFERENCES: These findings demonstrate that repeated exposure to MSG in mice leads to sensitization of jejunal afferent nerves to acute ex vivo exposure to MSG. This may contribute to visceral hypersensitivity reported in response to MSG in patients with IBS.

Multiple reproduction forms in the polyps of the cannonball jellyfish Stomolophus sp. 2: Probable life-cycle reversal.

The jellyfish genera Stomolophus spp. is one of the most abundant in the Pacific Ocean, yet it has not been thoroughly studied. Until recently, research has been developed and directed to its knowledge because of the economic interest in its exploitation. The genus Stomolophus in the Pacific Ocean is composed of five species (S. agaricus, S. chunii, S. collaris, S. fritillaria, and S. meleagris), and Stomolophus sp. 2 has been recently reported in the central part of the Gulf of California. Therefore, this study aimed to describe in vivo the different developmental stages of Stomolophus sp. 2 life cycle. As a result, multiple polyp reproduction forms were described, such as polyp-stolon formation, polydisc strobilation with more than 20 ephyrae formed by each strobila, and polyp formation directly from juvenile ephyra. In the degenerating phase, the polyps turned into cysts induced by stress conditions, such as changes in temperature, oxygen, and food availability. The life cycle of Stomolophus sp. 2 can be distinguished from that of S. meleagris by showing various asexual reproduction mechanisms and polydisc-like strobilation. The formation of polyps directly from the ectoderm of degenerating juvenile medusae suggests the possibility of a reversion cycle. Because of the different life cycles between S. meleagris and S. sp. 2, in addition to their morphological and genetic differences, this study proposes that Stomolophus sp. 2 should be considered a new species and suggests the name Stomolophus yaquilli, in reference to the indigenous community that lives in the species distribution area.

Histamine production by the gut microbiota induces visceral hyperalgesia through histamine 4 receptor signaling in mice.

The gut microbiota has been implicated in chronic pain disorders, including irritable bowel syndrome (IBS), yet specific pathophysiological mechanisms remain unclear. We showed that decreasing intake of fermentable carbohydrates improved abdominal pain in patients with IBS, and this was accompanied by changes in the gut microbiota and decreased urinary histamine concentrations. Here, we used germ-free mice colonized with fecal microbiota from patients with IBS to investigate the role of gut bacteria and the neuroactive mediator histamine in visceral hypersensitivity. Germ-free mice colonized with the fecal microbiota of patients with IBS who had high but not low urinary histamine developed visceral hyperalgesia and mast cell activation. When these mice were fed a diet with reduced fermentable carbohydrates, the animals showed a decrease in visceral hypersensitivity and mast cell accumulation in the colon. We observed that the fecal microbiota from patients with IBS with high but not low urinary histamine produced large amounts of histamine in vitro. We identified Klebsiella aerogenes, carrying a histidine decarboxylase gene variant, as a major producer of this histamine. This bacterial strain was highly abundant in the fecal microbiota of three independent cohorts of patients with IBS compared with healthy individuals. Pharmacological blockade of the histamine 4 receptor in vivo inhibited visceral hypersensitivity and decreased mast cell accumulation in the colon of germ-free mice colonized with the high histamine-producing IBS fecal microbiota. These results suggest that therapeutic strategies directed against bacterial histamine could help treat visceral hyperalgesia in a subset of patients with IBS with chronic abdominal pain.

Opioid-Induced Pronociceptive Signaling in the Gastrointestinal Tract Is Mediated by Delta-Opioid Receptor Signaling.

Opioid tolerance (OT) leads to dose escalation and serious side effects, including opioid-induced hyperalgesia (OIH). We sought to better understand the mechanisms underlying this event in the gastrointestinal tract. Chronic in vivo administration of morphine by intraperitoneal injection in male C57BL/6 mice evoked tolerance and evidence of OIH in an assay of colonic afferent nerve mechanosensitivity; this was inhibited by the δ-opioid receptor (DOPr) antagonist naltrindole when intraperitoneally injected in previous morphine administration. Patch-clamp studies of DRG neurons following overnight incubation with high concentrations of morphine, the µ-opioid receptors (MOPr) agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin (DAMGO) or the DOPr agonist [D-Ala2, D-Leu5]-Enkephalin evoked hyperexcitability. The pronociceptive actions of these opioids were blocked by the DOPr antagonist SDM25N but not the MOPr antagonist D-Pen-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 The hyperexcitability induced by DAMGO was reversed after a 1 h washout, but reapplication of low concentrations of DAMGO or [D-Ala2, D-Leu5]-Enkephalin restored the hyperexcitability, an effect mediated by protein kinase C. DOPr-dependent DRG neuron hyperexcitability was blocked by the endocytosis inhibitor Pitstop 2, and the weakly internalizing DOPr agonist ARM390 did not cause hyperexcitability. Bioluminescence resonance energy transfer studies in HEK cells showed no evidence of switching of G-protein signaling from Gi to a Gs pathway in response to either high concentrations or overnight incubation of opioids. Thus, chronic high-dose opioid exposure leads to opioid tolerance and features of OIH in the colon. This action is mediated by DOPr signaling and is dependent on receptor endocytosis and downstream protein kinase C signaling.SIGNIFICANCE STATEMENT Opioids are effective in the treatment of abdominal pain, but escalating doses can lead to opioid tolerance and potentially opioid-induced hyperalgesia. We found that δ-opioid receptor (DOPr) plays a central role in the development of opioid tolerance and opioid-induced hyperalgesia in colonic afferent nociceptors following prolonged exposure to high concentrations of MOPr or DOPr agonists. Furthermore, the role of DOPr was dependent on OPr internalization and activation of a protein kinase C signaling pathway. Thus, targeting DOPr or key components of the downstream signaling pathway could mitigate adverse side effects by opioids.

Changes in signalling from faecal neuroactive metabolites following dietary modulation of IBS pain.

OBJECTIVE: Dietary therapies for irritable bowel syndrome (IBS) have received increasing interest but predicting which patients will benefit remains a challenge due to a lack of mechanistic insight. We recently found evidence of a role for the microbiota in dietary modulation of pain signalling in a humanised mouse model of IBS. This randomised cross-over study aimed to test the hypothesis that pain relief following reduced consumption of fermentable carbohydrates is the result of changes in luminal neuroactive metabolites. DESIGN: IBS (Rome IV) participants underwent four trial periods: two non-intervention periods, followed by a diet low (LFD) and high in fermentable carbohydrates for 3 weeks each. At the end of each period, participants completed questionnaires and provided stool. The effects of faecal supernatants (FS) collected before (IBS FS) and after a LFD (LFD FS) on nociceptive afferent neurons were assessed in mice using patch-clamp and ex vivo colonic afferent nerve recording techniques. RESULTS: Total IBS symptom severity score and abdominal pain were reduced by the LFD (N=25; p<0.01). Excitability of neurons was increased in response to IBS FS, but this effect was reduced (p<0.01) with LFD FS from pain-responders. IBS FS from pain-responders increased mechanosensitivity of nociceptive afferent nerve axons (p<0.001), an effect lost following LFD FS administration (p=NS) or when IBS FS was administered in the presence of antagonists of histamine receptors or protease inhibitors. CONCLUSIONS: In a subset of IBS patients with improvement in abdominal pain following a LFD, there is a decrease in pronociceptive signalling from FS, suggesting that changes in luminal mediators may contribute to symptom response.

Agonist that activates the µ-opioid receptor in acidified microenvironments inhibits colitis pain without side effects.

OBJECTIVE: The effectiveness of µ-opioid receptor (MOPr) agonists for treatment of visceral pain is compromised by constipation, respiratory depression, sedation and addiction. We investigated whether a fentanyl analogue, (±)-N-(3-fluoro-1-phenethylpiperidine-4-yl)-N-phenyl propionamide (NFEPP), which preferentially activates MOPr in acidified diseased tissues, would inhibit pain in a preclinical model of inflammatory bowel disease (IBD) without side effects in healthy tissues. DESIGN: Antinociceptive actions of NFEPP and fentanyl were compared in control mice and mice with dextran sodium sulfate colitis by measuring visceromotor responses to colorectal distension. Patch clamp and extracellular recordings were used to assess nociceptor activation. Defecation, respiration and locomotion were assessed. Colonic migrating motor complexes were assessed by spatiotemporal mapping of isolated tissue. NFEPP-induced MOPr signalling and trafficking were studied in human embryonic kidney 293 cells. RESULTS: NFEPP inhibited visceromotor responses to colorectal distension in mice with colitis but not in control mice, consistent with acidification of the inflamed colon. Fentanyl inhibited responses in both groups. NFEPP inhibited the excitability of dorsal root ganglion neurons and suppressed mechanical sensitivity of colonic afferent fibres in acidified but not physiological conditions. Whereas fentanyl decreased defecation and caused respiratory depression and hyperactivity in mice with colitis, NFEPP was devoid of these effects. NFEPP did not affect colonic migrating motor complexes at physiological pH. NFEPP preferentially activated MOPr in acidified extracellular conditions to inhibit cAMP formation, recruit ß-arrestins and evoke MOPr endocytosis. CONCLUSION: In a preclinical IBD model, NFEPP preferentially activates MOPr in acidified microenvironments of inflamed tissues to induce antinociception without causing respiratory depression, constipation and hyperactivity.

Local immune response to food antigens drives meal-induced abdominal pain.

Up to 20% of people worldwide develop gastrointestinal symptoms following a meal1, leading to decreased quality of life, substantial morbidity and high medical costs. Although the interest of both the scientific and lay communities in this issue has increased markedly in recent years, with the worldwide introduction of gluten-free and other diets, the underlying mechanisms of food-induced abdominal complaints remain largely unknown. Here we show that a bacterial infection and bacterial toxins can trigger an immune response that leads to the production of dietary-antigen-specific IgE antibodies in mice, which are limited to the intestine. Following subsequent oral ingestion of the respective dietary antigen, an IgE- and mast-cell-dependent mechanism induced increased visceral pain. This aberrant pain signalling resulted from histamine receptor H1-mediated sensitization of visceral afferents. Moreover, injection of food antigens (gluten, wheat, soy and milk) into the rectosigmoid mucosa of patients with irritable bowel syndrome induced local oedema and mast cell activation. Our results identify and characterize a peripheral mechanism that underlies food-induced abdominal pain, thereby creating new possibilities for the treatment of irritable bowel syndrome and related abdominal pain disorders.

Endosomal signaling of delta opioid receptors is an endogenous mechanism and therapeutic target for relief from inflammatory pain.

Whether G protein-coupled receptors signal from endosomes to control important pathophysiological processes and are therapeutic targets is uncertain. We report that opioids from the inflamed colon activate δ-opioid receptors (DOPr) in endosomes of nociceptors. Biopsy samples of inflamed colonic mucosa from patients and mice with colitis released opioids that activated DOPr on nociceptors to cause a sustained decrease in excitability. DOPr agonists inhibited mechanically sensitive colonic nociceptors. DOPr endocytosis and endosomal signaling by protein kinase C (PKC) and extracellular signal-regulated kinase (ERK) pathways mediated the sustained inhibitory actions of endogenous opioids and DOPr agonists. DOPr agonists stimulated the recruitment of Gαi/o and ß-arrestin1/2 to endosomes. Analysis of compartmentalized signaling revealed a requirement of DOPr endocytosis for activation of PKC at the plasma membrane and in the cytosol and ERK in the nucleus. We explored a nanoparticle delivery strategy to evaluate whether endosomal DOPr might be a therapeutic target for pain. The DOPr agonist DADLE was coupled to a liposome shell for targeting DOPr-positive nociceptors and incorporated into a mesoporous silica core for release in the acidic and reducing endosomal environment. Nanoparticles activated DOPr at the plasma membrane, were preferentially endocytosed by DOPr-expressing cells, and were delivered to DOPr-positive early endosomes. Nanoparticles caused a long-lasting activation of DOPr in endosomes, which provided sustained inhibition of nociceptor excitability and relief from inflammatory pain. Conversely, nanoparticles containing a DOPr antagonist abolished the sustained inhibitory effects of DADLE. Thus, DOPr in endosomes is an endogenous mechanism and a therapeutic target for relief from chronic inflammatory pain.

The impact of dietary fermentable carbohydrates on a postinflammatory model of irritable bowel syndrome.

BACKGROUND: A low fermentable carbohydrate (FODMAP) diet is used in quiescent inflammatory bowel disease when irritable bowel syndrome-like symptoms occur. There is concern that the diet could exacerbate inflammation by modifying microbiota and short-chain fatty acid (SCFA) production. We examined the effect of altering dietary FODMAP content on inflammation in preclinical inflammatory models. METHODS: C57BL/6 mice were given 3% dextran sodium sulfate (DSS) in drinking water for 5 days and recovered for 3 weeks (postinflammatory, n = 12), or 5 days (positive-control, n = 12). Following recovery, DSS-treated or control mice (negative-control, n = 12) were randomized to 2-week low- (0.51 g/100 g total FODMAP) or high-FODMAP (4.10 g) diets. Diets mimicked human consumption containing fructose, sorbitol, galacto-oligosaccharide, and fructan. Colons were assessed for myeloperoxidase (MPO) activity and histological damage. Supernatants were generated for perforated patch-clamp recordings and cytokine measurement. Cecum contents were analyzed for microbiota, SCFA, and branched-chain fatty acids (BCFA). Data were analyzed by two-way ANOVA with Bonferroni. KEY RESULTS: Inflammatory markers were higher in the positive-control compared with negative-control and postinflammatory groups, but no differences occurred between the two diets within each treatment (MPO P > .99, histological scores P > .99, cytokines P > .05), or the perforated patch-clamp recordings (P > .05). Microbiota clustered mainly based on DSS exposure. No difference in SCFA content occurred. Higher total BCFA occurred with the low-FODMAP diet in positive-control (P < .01) and postinflammatory groups (P < .01). CONCLUSIONS AND INFERENCES: In this preclinical study, reducing dietary FODMAPs did not exacerbate nor mitigate inflammation. Microbiota profile changes were largely driven by inflammation rather than diet. Low FODMAP intake caused a shift toward proteolytic fermentation following inflammation.

Protein kinase D and Gßγ mediate sustained nociceptive signaling by biased agonists of protease-activated receptor-2.

Proteases sustain hyperexcitability and pain by cleaving protease-activated receptor-2 (PAR2) on nociceptors through distinct mechanisms. Whereas trypsin induces PAR2 coupling to Gαq, Gαs, and ß-arrestins, cathepsin-S (CS) and neutrophil elastase (NE) cleave PAR2 at distinct sites and activate it by biased mechanisms that induce coupling to Gαs, but not to Gαq or ß-arrestins. Because proteases activate PAR2 by irreversible cleavage, and activated PAR2 is degraded in lysosomes, sustained extracellular protease-mediated signaling requires mobilization of intact PAR2 from the Golgi apparatus or de novo synthesis of new receptors by incompletely understood mechanisms. We found here that trypsin, CS, and NE stimulate PAR2-dependent activation of protein kinase D (PKD) in the Golgi of HEK293 cells, in which PKD regulates protein trafficking. The proteases stimulated translocation of the PKD activator Gßγ to the Golgi, coinciding with PAR2 mobilization from the Golgi. Proteases also induced translocation of a photoconverted PAR2-Kaede fusion protein from the Golgi to the plasma membrane of KNRK cells. After incubation of HEK293 cells and dorsal root ganglia neurons with CS, NE, or trypsin, PAR2 responsiveness initially declined, consistent with PAR2 cleavage and desensitization, and then gradually recovered. Inhibitors of PKD, Gßγ, and protein translation inhibited recovery of PAR2 responsiveness. PKD and Gßγ inhibitors also attenuated protease-evoked mechanical allodynia in mice. We conclude that proteases that activate PAR2 by canonical and biased mechanisms stimulate PKD in the Golgi; PAR2 mobilization and de novo synthesis repopulate the cell surface with intact receptors and sustain nociceptive signaling by extracellular proteases.

Epithelial expression and function of trypsin-3 in irritable bowel syndrome.

OBJECTIVES: Proteases are key mediators of pain and altered enteric neuronal signalling, although the types and sources of these important intestinal mediators are unknown. We hypothesised that intestinal epithelium is a major source of trypsin-like activity in patients with IBS and this activity signals to primary afferent and enteric nerves and induces visceral hypersensitivity. DESIGN: Trypsin-like activity was determined in tissues from patients with IBS and in supernatants of Caco-2 cells stimulated or not. These supernatants were also applied to cultures of primary afferents. mRNA isoforms of trypsin (PRSS1, 2 and 3) were detected by reverse transcription-PCR, and trypsin-3 protein expression was studied by western blot analysis and immunohistochemistry. Electrophysiological recordings and Ca2+ imaging in response to trypsin-3 were performed in mouse primary afferent and in human submucosal neurons, respectively. Visceromotor response to colorectal distension was recorded in mice administered intracolonically with trypsin-3. RESULTS: We showed that stimulated intestinal epithelial cells released trypsin-like activity specifically from the basolateral side. This activity was able to activate sensory neurons. In colons of patients with IBS, increased trypsin-like activity was associated with the epithelium. We identified that trypsin-3 was the only form of trypsin upregulated in stimulated intestinal epithelial cells and in tissues from patients with IBS. Trypsin-3 was able to signal to human submucosal enteric neurons and mouse sensory neurons, and to induce visceral hypersensitivity in vivo, all by a protease-activated receptor-2-dependent mechanism. CONCLUSIONS: In IBS, the intestinal epithelium produces and releases the active protease trypsin-3, which is able to signal to enteric neurons and to induce visceral hypersensitivity.

Stress activates pronociceptive endogenous opioid signalling in DRG neurons during chronic colitis.

AIMS AND BACKGROUND: Psychological stress accompanies chronic inflammatory diseases such as IBD, and stress hormones can exacerbate pain signalling. In contrast, the endogenous opioid system has an important analgesic action during chronic inflammation. This study examined the interaction of these pathways. METHODS: Mouse nociceptive dorsal root ganglia (DRG) neurons were incubated with supernatants from segments of inflamed colon collected from patients with chronic UC and mice with dextran sodium sulfate (cDSS)-induced chronic colitis. Stress effects were studied by adding stress hormones (epinephrine and corticosterone) to dissociated neurons or by exposing cDSS mice to water avoidance stress. Changes in excitability of colonic DRG nociceptors were measured using patch clamp and Ca2+ imaging techniques. RESULTS: Supernatants from patients with chronic UC and from colons of mice with chronic colitis caused a naloxone-sensitive inhibition of neuronal excitability and capsaicin-evoked Ca2+ responses. Stress hormones decreased signalling induced by human and mouse supernatants. This effect resulted from stress hormones signalling directly to DRG neurons and indirectly through signalling to the immune system, leading to decreased opioid levels and increased acute inflammation. The net effect of stress was a change endogenous opioid signalling in DRG neurons from an inhibitory to an excitatory effect. This switch was associated with a change in G protein-coupled receptor excitatory signalling to a pathway sensitive to inhibitors of protein kinase A-protein, phospholipase C-protein and G protein ßϒ subunits. CONCLUSIONS: Stress hormones block the inhibitory actions of endogenous opioids and can change the effect of opioid signalling in DRG neurons to excitation. Targeting these pathways may prevent heavy opioid use in IBD.

Two P2X1 receptor transcripts able to form functional channels are present in most human monocytes.

To characterize the presence and general properties of P2X1 receptors in single human monocytes we used RT-PCR, flow cytometry, and the patch-clamp and the two-electrode voltage-clamp techniques. Most human monocytes expressed the canonical P2X1 (90%) and its splicing variant P2X1del (88%) mRNAs. P2X1 receptor immunoreactivity was also observed in 70% of these cells. Currents mediated by P2X1 (EC50=1.9±0.8µm) and P2X1del (EC50 >1000µm) channels, expressed in Xenopus leavis oocytes, have different ATP sensitivity and kinetics. Both currents mediated by P2X1 and P2X1del channels kept increasing during the continuous presence of high ATP concentrations. Currents mediated by the native P2X1 receptors in human monocytes showed an EC50=6.3±0.2µm. Currents have kinetics that resemble those observed for P2X1 and P2X1del receptors in oocytes. Our study is the first to demonstrate the expression of P2X1 transcript and its splicing variant P2X1del in most human monocytes. We also, for the first time, described functional homomeric P2X1del channels and demonstrated that currents mediated by P2X1 or P2X1del receptors, during heterologous expression, increased in amplitude when activated with high ATP concentrations in a similar fashion to those channels that increase their conductance under similar conditions, such as P2X7, P2X2, and P2X4 channels.

Evaluation of the expression and function of the P2X7 receptor and ART1 in human regulatory T-cell subsets.

Regulatory T cells that express CD39 (CD39+ Treg) exhibit specific immunomodulatory properties. Ectonucleotidase CD39 hydrolyses ATP and ADP. ATP is a ligand of the P2X7 receptor and induces the shedding of CD62L and apoptosis. However, the role of ATP in CD39+ Treg cells has not been defined. Furthermore, NAD can activate the P2X7 receptor via ADP-ribosyltransferase (ART) enzymes and cause cell depletion in murine models. We evaluated the expression and function of P2X7 and ART1 in CD39+ Treg and CD39- Treg cells in the presence or absence of ATP and NAD. We isolated peripheral blood mononuclear cells from healthy subjects and purified CD4+ T cells, CD4+ CD25+ T cells and CD4+ CD25+ CD39+ T cells. P2X7 and ART1 expression was assessed by flow cytometry and real-time PCR. Our results showed low P2X7 expression on CD39+ Treg cells and higher levels of ART1 expression in CD4+ CD39+ T cells than the other subtypes studied. Neither shedding of CD62L nor cell death of CD39+ Treg or CD39- Treg cells was observed by 1mM ATP or 60µM NAD. In contrast, P2Xs receptor-dependent proliferation with 300µM ATP, was inhibited by NAD in the different cell types analysed. The NAD proliferation-inhibition was increased with P2Xs and A2a agonist and was reversed with P2Xs and A2a antagonist, therefore NAD inhibits P2Xs-dependent proliferation and A2a activation. In conclusion, our results suggest that the altered function and expression of P2X7 and ART1 in the human CD39+ Treg or CD39- Treg cells could participate in the resistance against cell death induced by ATP or NAD.

ATP releases ATP or other nucleotides from human peripheral blood leukocytes through purinergic P2 receptors.

AIMS: Almost every eukaryotic cell releases ATP under certain conditions. The idea that ATP induces the release of ATP has been scantly investigated. METHODS: We explored this possibility by assessing the rate of exogenous ATP breakdown (measured by phosphates production) by human peripheral blood leukocytes. The role of P2Y and P2X receptors was evaluated pharmacologically, by patch clamp, or by flow cytometry. KEY FINDINGS: In mononuclear and/or polymorphonuclear cells, ATP increased phosphates formation in a time- and concentration-dependent manner. Uncoupling of P2Y receptors with N-ethylmaleimide and antagonism of P2Y and P2X receptors through suramin reduced phosphate formation after 500µM ATP, suggesting that part of the phosphate production was due to activation of P2 receptors, with subsequent release of ATP or other nucleotides. Similar results were obtained with UTP and ATPγS. Gadolinium (connexins inhibitor) also significantly reduced the ATP-induced phosphate production. Blockade of P2X receptors with SKF 96365 or NF023 did not modify the phosphate production. In monocytes, 500µM ATP induced inward currents suggestive of P2X1 activation, but higher concentrations (1-5mM) induced inward currents suggestive of P2X7 activation. We discarded a role of adenosine in the ATP-evoked nucleotides release. Flow cytometry identified that almost all mononuclear and polymorphonuclear cells expressed P2Y1,2,4,6,11 receptors. SIGNIFICANCE: 500µM ATP induced the release of ATP or other nucleotides through activation of P2Y2,4,6,11 receptors in human leukocytes, and probably via P2X receptors at higher concentrations. This ATP-induced nucleotides release constitutes a potential mechanism leading to amplification of ATP signaling.

Nutricion infantil: natural o artificial...? / Children nutrition: natural or artificial...?

La promocion y comercializacion, al margen de un marco etico de los mal llamados "sucedaneos de la leche materna", por parte de la poderosa industria transnacional y de la propia industria nacional, estan incitando el consumo, aun exponiendo las vidas de infantes y niños indefensos, de estos mal llamdos "substitutos de la leche materna". Cuando mas prematuramente los lactantes son destetados y privados del alimento natural suministrado por sus madres, la leche materna, mas contribuyen a un saludable negocio que pone en riesgo, imprudentemente, la apropiada nutricion infantil. El presente articulo muestra los resultados de un monitoreo efectuado, en las ciudades de La Paz y El alto en el año 1977, indagando sobre la situacion, implementada y cumplimiento del codigo internacional del reglamento nacional y el convenio entre autoridades, productores y distribuidores de sucedaneos de la leche materna, en el pais

Dependencia por receta médica: La comercialización de benzodiazepinas en el tercer mundo / sss

La obra describe los antecedentes de este grupo de fármacos, su actual situación e impacto, asi como los resultados de una investigación conducida por los autores, sobre su uso en la terapeútica médica por sus propiedades sedantes, antiansiosas, hipnoinductoras, relajantes y musculares y anticonvulsivantes. Sus primeras propiedades les ha valido el denominativo de "pastillas rosadas para el alma" por el abuso de ellas para estos fines